This invention relates generally to pickup systems for electrical musical instruments and more particularly, but not by way of limitation, to switchable hum-canceling windings for electric guitars.
One technique for amplifying the sound of a stringed musical instrument uses electromagnetic pickups positioned beneath the strings of the instrument. Such pickups include one or more coils or windings of wire wrapped around one or more metallic cores or pole pieces which are themselves magnetic or which are magnetized by adjacent magnetic material. The strings of the instrument pass through the magnetic field and cause an electrical signal to be produced in the winding(s) when the strings vibrate within the magnetic field in response to being played. The produced electrical signals correspond to the notes played on the strings, and the electrical signals are electrically amplified and broadcast to create the amplified audible music.
Of particular relevance to the present invention is the single-coil pickup, which is a type of pickup that typically has a brighter tone than a conventional multiple-coil humbucker pickup. This single-coil type of pickup is known to have a shortcoming due to its tendency to respond not only to the adjacent string vibration but also to ambient electromagnetic interference. This interference arises from other electrical devices (e.g., lights, motors, transformers, etc.) in the area which are powered by conventional alternating current power (at a frequency of 60-hertz in the United States, for example). This produces distortion, such as a 60-hertz hum, in the amplified music.
Although this problem is well-known and despite various proposed or implemented solutions for canceling this hum, there is still the need for a hum-canceling pickup system which is relatively simple and inexpensive to implement yet which allows for different tonalities to be selected by the player and which also enables relatively high power output and which still retains the bright tonality of a single-coil pickup.